cnic: Fix __symbol_get() build error.

Ingo molnar <mingo@elte.hu> reported the error

drivers/net/cnic.c:2520: error: implicit declaration of function ‘__symbol_get’

when CONFIG_MODULES is not defined.  Fix by using symbol_get() instead.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>